JP2006091134A - Image blur correcting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image blur correcting device in which a vibration applied to an optical system is detected using a low-pass stable gyro which has little drift but has poor frequency characteristics and a high-pass gyro which has a large amount of drift but has satisfactory frequency characteristics in a high-pass region, an angular velocity signal in the region of a lower frequency than a predetermined switching frequency is obtained from the low-pass stable gyro sensor and an angular velocity signal in the region of a higher frequency than the switching frequency is obtained from the high-pass gyro sensor having satisfactory characteristics in the hi-pass region, the angular velocity signals are composited, thereby an angular velocity signal having less drift and satisfactory frequency characteristics is generated, the switching frequency is changed according to presence or no presence of vibration and thereby the appropriate angular velocity signals can be composited according to the states vibration. <P>SOLUTION: Angular velocity signals of a vibration applied to the optical system are obtained from the low-pass stable gyro sensor 30L and satisfactory high-pass characteristic gyro sensor 30H. The angular velocity signals are composited by a composition circuit 36. The switching frequency in the composition circuit 36 is changed by a CPU 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image shake correction apparatus, and more particularly to an image shake correction apparatus that corrects (prevents) image shake of a camera due to vibration.

As an image shake correction device for a TV camera, an anti-vibration lens is placed in the photographic optical system so that it can move in a plane perpendicular to the optical axis. An image stabilization lens is driven by an actuator so as to cancel the image to correct image blur (see, for example, Patent Documents 1 and 2). The amount of displacement of the anti-vibration lens for canceling the image blur is calculated, for example, by detecting vibration applied to the camera by an angular velocity sensor and integrating the angular velocity signal output from the angular velocity sensor.
JP 2001-142103 A JP 2003-107554 A

  Incidentally, it is known that the angular velocity sensor has a characteristic called drift in which the zero point varies with time due to heat or the like. The angular velocity sensors currently on the market can be roughly classified into two types according to the drift characteristics and the phase-related frequency characteristics. One with low drift but poor frequency characteristics (the higher the frequency, the larger the phase lag), and the other with much drift but good frequency characteristics (even when the frequency is high, the phase lag is small) are categorized. If the one classified as the former is called an angular velocity sensor with good drift characteristics, and the one classified as the latter is called an angular velocity sensor with good frequency characteristics, drift will occur when an angular velocity sensor with good drift characteristics is used for image blur correction. However, since the phase lag is large, it is necessary to compensate for the phase lag, and there is a problem that over-correction is caused with respect to the vibration in the high frequency region due to the increase in gain associated therewith.

  On the other hand, when an angular velocity sensor with good frequency characteristics is used for image blur correction, even if the phase lag is compensated for because the phase lag is small, overcorrection is hardly a problem, but there is no vibration because the drift is large. However, it is misunderstood that vibration has occurred, and image blur correction is performed. As a result, there is a problem that the image moves (so-called “fluctuation”) and a stable image cannot be obtained. In particular, in a photographing lens used for television broadcasting, zooming has been performed at a higher magnification. When the zoom magnification is large, the fluctuation becomes more conspicuous, and it is an important issue to prevent drift. When the drift signal component is removed with a high-pass filter, etc., the drift frequency component and the vibration frequency region subject to image blur correction partially overlap. There is also a problem that image blur correction for the vibration in the removed frequency range is not performed properly.

  The present invention has been made in view of such circumstances, and there is little image fluctuation due to drift of a shake sensor such as an angular velocity sensor that detects vibration, and good image shake correction is performed for vibrations in a wide range of frequencies. An object of the present invention is to provide an image blur correction apparatus that can be used.

  In order to achieve the object, an image shake correction apparatus according to claim 1, an optical system that forms an image, and a shake signal output unit that outputs a shake signal corresponding to the vibration applied to the optical system, An image displacing means for displacing the image, and an image for displacing the image by the image displacing means so as to cancel image blur caused by vibration applied to the optical system based on a shake signal output by the shake signal output means. In the image shake correction apparatus including the shake correction unit, the shake signal output unit is a first shake sensor that outputs a shake signal corresponding to the vibration applied to the optical system, and has a low frequency but a high frequency. A first shake sensor having a poor frequency characteristic in a region, and a second shake sensor that outputs a shake signal corresponding to the vibration applied to the optical system, wherein drift is higher than that of the first shake sensor. However, a second shake sensor having a good frequency characteristic in a high frequency region, a shake signal in a low frequency region lower than a predetermined switching frequency is acquired from the first shake sensor, and a shake signal in a higher frequency region than the switching frequency is obtained. By synthesizing and synthesizing from the second shake sensor to generate a shake signal for the entire frequency region of vibration applied to the optical system, and a switching frequency for changing the switching frequency in the signal synthesis means And a changing means.

  According to the present invention, a vibration signal in a low frequency region is obtained from a vibration sensor having a good drift characteristic, and a vibration signal in a high frequency region is obtained from a vibration sensor having a good frequency characteristic in a high frequency region and synthesized, thereby synthesizing all vibration frequencies. Since the shake signal in the region is acquired, a shake signal with little drift and excellent frequency characteristics can be obtained. In particular, since the switching frequency that divides the frequency domain of the shake signal to be synthesized when the shake signals output from the first and second shake sensors are synthesized can be changed, the vibration status can be changed. It is possible to synthesize a more appropriate shake signal according to the above.

  According to a second aspect of the present invention, in the image blur correction apparatus according to the first aspect, the switching frequency changing unit changes the switching frequency based on the magnitude of vibration applied to the optical system. It is said. According to the present invention, which of the drift characteristic and the frequency characteristic is given priority as a suitable characteristic of the shake sensor differs depending on the magnitude of vibration, and therefore the switching frequency is changed based on the magnitude of vibration.

  According to a third aspect of the present invention, in the image blur correction device according to the second aspect, the switching frequency changing unit is a vibration applied to the optical system based on a shake signal obtained from the first shake sensor. It is characterized by detecting the size of. In order to detect the magnitude of vibration, it is more appropriate to make a determination using the shake signal of the first shake sensor with little drift.

  According to a fourth aspect of the present invention, in the image blur correction device according to the second or third aspect, the switching frequency changing unit is configured to determine that the magnitude of vibration applied to the optical system is no vibration. The switching frequency is divided into the size determined to have vibration, and the switching frequency is increased when the size is determined to be no vibration compared to the size determined to be vibration. According to the present invention, when it is determined that there is no vibration, it is important that no drift occurs. Therefore, the shake signal from the first shake sensor with little drift is effectively used in a wide frequency range. Like to do.

  According to a fifth aspect of the present invention, in the image blur correction apparatus according to any one of the first to fourth aspects, the image displacing unit displaces an image stabilizing lens disposed in the optical system. It is characterized by displacing. The present invention employs optical correction using an anti-vibration lens as an image blur correction method.

  According to the image shake correction apparatus of the present invention, image fluctuation due to drift of the shake sensor is small, and image shake can be suitably prevented with respect to vibrations in a wide range of frequencies.

  A preferred embodiment of an image blur correction apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing the internal configuration of an image blur correction apparatus according to the present invention. The image blur correction device is mounted on, for example, a lens device (photographing lens) for a television camera, a movie camera, a still camera, or the like, and the image stabilization lens 24 shown in FIG. It is arranged in an optical system such as a camera, and is arranged so as to be movable up and down (vertical direction) and left and right (horizontal direction) in a plane perpendicular to the optical axis of the optical system. The anti-vibration lens 24 is driven up and down or left and right by the motor 22, and when vibration occurs in the camera (optical system), the position at which the image blur is corrected by the motor 22. It moves to (position where image shake due to vibration is canceled). The anti-vibration lens 24 is driven in the same manner in both the vertical and horizontal directions based on the vibration generated in each direction, and therefore the image blur correction in one direction (for example, the horizontal direction) is shown in FIG. Only the configuration to be performed is shown, and the configuration is the same for other directions.

  An angular velocity signal output unit 10 shown in FIG. 1 is a component that detects an angular velocity of vibration generated in the optical system and outputs a detected angular velocity signal (angular velocity signal) as a shake signal. For example, left and right vibrations of the optical system are detected by two angular velocity sensors 30L and 30H having different angles, and an angular velocity signal S3 obtained by synthesizing the angular velocity signals output from the respective angular velocity sensors 30L and 30H is output.

  The angular velocity signal S3 output from the angular velocity signal output unit 10 is subjected to digital filtering by the A / D converter 14 after the low frequency filter (LPF) 12 blocks a frequency component higher than the frequency range targeted for image blur correction. It is converted into a signal and input to the CPU 16.

  The CPU 16 integrates the input angular velocity signal S3 by arithmetic processing equivalent to a digital filter, and converts the angular velocity signal S3 into an angle signal. That is, the amount of displacement of the image stabilizing lens 24 (the amount of displacement from the reference position) for displacing the image in the direction and size to cancel the image shake caused by the vibration of the optical system, and the angular velocity signal S3 are integrated. By seeking. Then, the value of the angle signal is output as a value indicating the movement target position of the image stabilizing lens 24.

  The angle signal output from the CPU 16 is converted into an analog signal by the D / A converter 18 and then input to the motor drive circuit 20. The motor drive circuit 20 drives the motor 22 that moves the image stabilization lens 24 in the left-right direction, for example, and moves the image stabilization lens 24 to a position corresponding to the value of the angle signal output from the CPU 16. As a result, image blur due to vibration applied to the optical system is corrected.

  Note that the image blur correction method includes not only the case where the image blur is canceled by the image displacing means for intentionally displacing the image of the optical system by displacing the image stabilizing lens 24 as in the present embodiment. An image displacement means that intentionally displaces the image by displacing the image sensor, and the image blur is canceled by an image displacement means, or the image blur is not corrected by an optical image displacement means. There is known a technique in which image blur is canceled by electronic image displacement means for intentionally displacing an image by displacing a range cut out as a video signal for recording or reproduction from the range of a captured image. In such other types of image blur correction, by integrating the angular velocity signal obtained from the angular velocity signal output unit 10, an image is transferred to the image displacement means so as to cancel the image blur as in the present embodiment. A displacement amount signal (corresponding to the angle signal) for displacement can be obtained, and the present invention can be applied to other types of image blur correction as in the present embodiment.

  Next, the angular velocity signal output unit 10 will be described in detail. The two angular velocity sensors 30L and 30H that detect vibrations of the optical system are, for example, gyro sensors, and are installed on the upper surface of the lens barrel. From each of the angular velocity sensors 30L and 30H, an electric signal having a voltage corresponding to the angular velocity of vibration generated in, for example, the left-right direction of the lens barrel is output as an angular velocity signal.

  These two angular velocity sensors 30L and 30H have different characteristics, and the angular velocity sensor 30L uses a sensor with little drift but poor frequency characteristics (an angular velocity sensor with good drift characteristics). For 30H, a sensor that has a lot of drift but good frequency characteristics (an angular velocity sensor with good frequency characteristics) is used.

  FIG. 2 is a characteristic diagram comparing the frequency characteristics of these angular velocity sensors 30L and 30H. FIG. 2A shows frequency characteristics (gain characteristics) relating to gain, and the angular characteristics of both angular velocity sensors 30L and 30H are substantially the same with respect to gain characteristics. On the other hand, FIG. 5B shows the frequency characteristics (phase characteristics) related to the phase, the curve A shows the phase characteristics of the angular velocity sensor 30L, and the curve B shows the phase characteristics of the angular velocity sensor 30H. As can be seen by comparing the curve A and the curve B, the angular velocity sensor 30H shows good phase characteristics with little phase lag even in a high frequency region, whereas the angular velocity sensor 30L has a higher phase in the region where the frequency is high. The delay is remarkably large and the phase characteristics are poor.

  On the other hand, with respect to the drift characteristics that do not appear in these characteristic diagrams, the angular velocity sensor 30L has a smaller drift than the angular velocity sensor 30H and exhibits a favorable characteristic.

  The angular velocity sensor 30L is referred to as a low-frequency stable gyro 30L, and the angular velocity sensor 30H is referred to as a high-frequency characteristic gyro 30H.

  As shown in FIG. 1, the angular velocity signals output from the low frequency stable gyro 30L and the high frequency characteristic gyro 30H are respectively removed from the DC component by the DC cut units 32L and 32H, and amplified by the amplifier circuits 34L and 34H. After being processed, it is input to the synthesis circuit 36. Note that the angular velocity signal obtained from the low frequency stable gyro 30L is S1, and the angular velocity signal obtained from the high frequency characteristic gyro 30H is S2.

  The synthesis circuit 36 is divided into two frequency regions, a low frequency region fL and a high frequency region fH, with a predetermined frequency (switching frequency) as a boundary, and is obtained from each of the low frequency stable gyro 30L and the high frequency characteristic gyro 30H. Among the angular velocity signals S1 and S2, the signal component in the low frequency region fL is acquired from the angular velocity signal S1 of the low frequency stable gyro 30L with good drift characteristics, and the signal component in the high frequency region fH is excellent in high frequency characteristics with good frequency characteristics. Obtained from the angular velocity signal S2 of the gyro 30H, and combines them to generate an angular velocity signal S3 in the entire frequency region.

  FIG. 3 shows an example of the synthesis circuit 36. As shown in the figure, when the angular velocity signal S1 from the low-frequency stable gyro 30L and the angular velocity signal S2 from the high-frequency characteristic gyro 30H are input to the synthesis circuit 36, the difference signal S2-S1 is converted into a high-pass filter ( HPF) 50. As a result, a signal on the lower frequency side than the cutoff frequency fc of the HPF 50 is cut off from the difference signal S2-S1, and only a signal on the higher frequency side than the cutoff frequency fc is output from the HPF 50. Then, the angular velocity signal S1 inputted from the low-frequency stable gyro 30L is added to the signal outputted from the HPF 50, and the signal is outputted from the synthesis circuit 36 as the angular velocity signal S3.

  FIG. 4 is a diagram showing the frequency characteristics of the synthesis circuit 36. The characteristics of the synthesis circuit 36 with respect to the angular velocity signal S1 input from the low-frequency stable gyro 30L are represented by a graph L1, and the high-frequency characteristics good gyro 30H The characteristic of the synthesis circuit 36 with respect to the angular velocity signal S2 is represented by a graph L2. As shown by these characteristics, among the angular velocity signals S3 output from the synthesis circuit 36 with the cutoff frequency fc of the HPF 50 as a boundary, the signal in the low frequency region fL on the lower frequency side than the cutoff frequency fc is stable in the low frequency range. A signal in the high frequency region fH higher than the cut-off frequency fc is generated from the angular velocity signal S1 from the gyro 30L, and is generated from the angular velocity signal S2 from the high frequency characteristic gyro 30H. That is, the synthesizing circuit 36 has an LPF having the characteristics of the graph L1 to which the angular velocity signal S1 from the low frequency stable gyro 30L is input and the characteristics of the graph L2 to which the angular velocity signal S2 from the high frequency characteristic gyro 30H is input. It is equivalent to a circuit composed of an HPF having an adder and an adder for adding the outputs of these LPF and HPF.

  The cut-off frequency fc of the HPF 50 is switched depending on the presence or absence of vibration of the optical system as will be described later. For example, when it is determined that there is vibration, it is set to 4 Hz. . The cut-off frequency fc of the HPF 50 is a frequency crossover frequency where the graph L1 indicating the LPF characteristic and the graph L2 indicating the HPF characteristic intersect, and the frequency when the synthesizing circuit 36 generates the angular velocity signal S3. The region is divided into a low-frequency region and a high-frequency region, and a sensor that generates an angular velocity signal in the low-frequency region and a sensor that generates an angular velocity signal in the high-frequency region are switched to a frequency that switches from the low-frequency stable gyro 30L to the high-frequency characteristic gyro 30H. Equivalent to. This frequency is assumed to be fC, and the switching frequency fC of the synthesizing circuit 36, or the switching frequency fC (or simply the switching frequency fC) of the synthesized gyro that outputs the angular velocity signal obtained by synthesizing the outputs of the low frequency stable gyro 30L and the high frequency characteristic gyro 30H. ).

  The angular velocity signal S3 synthesized by the synthesizing circuit 36 is obtained by the angular velocity signal S1 obtained from the low-frequency stable gyro 30L having a good drift characteristic in the low-frequency region fL lower than the switching frequency fC. Therefore, even if the angular velocity signal S1 is obtained from the low-frequency stable gyro 30L having poor frequency characteristics, the angular velocity signal S1 is effectively used only in the low-frequency region fL. Therefore, the frequency characteristics in the low frequency region fL are also good. On the other hand, since the signal component of the high frequency region fH on the higher frequency side than the switching frequency fC is generated by the angular velocity signal S2 obtained from the high frequency characteristic gyro 30H having good frequency characteristics, the frequency characteristics in the high frequency region fH are also obtained. It is good.

  Therefore, the angular velocity signal S3 synthesized by the synthesizing circuit 36 and outputted from the angular velocity signal output unit 10 to the LPF 12 as described above is equivalent to a signal obtained from an angular velocity sensor (synthetic gyro) with little drift and good frequency characteristics. It becomes.

  By the way, comparing the case where the vibration hardly occurs in the optical system and the case where the vibration does not occur, when the vibration hardly occurs in the optical system, the drift is less than the good frequency characteristic (the drift characteristic is good). This is very important. Considering the case where a certain amount of vibration is generated in the optical system, the switching frequency fC of the synthesis circuit 36 is determined so that both the drift characteristic and the frequency characteristic are good and fixed to that value. When vibration hardly occurs, voltage fluctuation due to drift generated in the high frequency characteristic gyro 30H appears in the angular velocity signal S3, and image fluctuation due to the fluctuation may not be negligible.

  Therefore, in the present embodiment, by changing the switching frequency fC of the synthesis circuit 36, a more appropriate angular velocity signal S3 can be obtained from the synthesis circuit 36 according to the magnitude of vibration or the like.

  In FIG. 1, the angular velocity signal S1 obtained from the low-frequency stable gyro 30L is branched before being input to the synthesis circuit 36 and is input to a low-pass filter (LPF) 38, and the image blur correction is performed by the LPF 38. After a frequency component higher than the target frequency range is cut off, it is converted into a digital signal by the A / D converter 14 and given to the CPU 16. The CPU 16 determines the presence or absence of vibration of the optical system based on the signal (low range stable gyro signal) obtained only from the angular velocity signal S1 of the low range stable gyro 30L in this way. For example, when the value of the low-frequency stable gyro signal is smaller than a predetermined threshold A, it is determined that there is no vibration, and when it is greater than or equal to the threshold A, it is determined that there is vibration. Then, the CPU 16 outputs a switching signal to the synthesis circuit 36 in order to switch the value of the switching frequency fC based on the determination.

  The signal used to determine the presence or absence (vibration magnitude) of the optical system is preferably the angular velocity signal S1 of the low-pass stable gyro 30L with little drift, but is not limited thereto, and is synthesized by the synthesis circuit 36. Alternatively, the angular velocity signal S3 or the angular velocity signal S2 of the high frequency characteristic gyro 30H may be used. Further, the presence or absence of vibration may be determined using a signal after integrating the angular velocity signal.

  The switching frequency fC in the synthesis circuit 36 is switched by switching the cutoff frequency fc of the HPF 50 of the synthesis circuit 36 shown in FIG. FIG. 5 is a diagram illustrating an example of the circuit configuration of the HPF 50. As shown in the figure, the non-inverting input terminal 1 of the operational amplifier OP1 is fixed to a constant potential (ground potential), and the inverting input terminal 2 is connected to the input terminal 50A of the HPF 50 via a resistor R1 and a capacitor C1. On the other hand, the output terminal 3 of the operational amplifier OP1 is connected to the output terminal 50B of the HPF 50, and a resistor R2 is connected between the output terminal 3 and the inverting input terminal 2 of the operational amplifier OP1. As a result, a high-pass filter having a cutoff frequency determined by the resistance values of the resistors R1 and R2 and the value of C1 is formed.

  On the other hand, the resistor R1 'and the switch SW1 are connected in parallel to the resistor R1, and the resistor R2' and the switch SW2 are connected in parallel to the resistor R2, and the switch SW1 and the switch SW2 are On / off is switched by a switching signal given from the CPU 16. When the switches SW1 and SW2 are turned on and off, the resistance values at the resistors R1 and R2 change, so that the cutoff frequency fc of the HPF 50 also changes. For example, the cutoff frequency fc when the switch SW1 and the switch SW2 are off is a suitable Fv when it is determined that the optical system is vibrated, and the cutoff frequency fc when the switch SW1 and the switch SW2 are on is the optical frequency. When it is determined that there is no vibration in the system, it is switched to a suitable Fs (> Fv).

  By switching the cut-off frequency fc of the HPF 50 in this way, the switching frequency fC (= fc) of the synthesis circuit 36 is switched, and the switching frequency fC is higher in the situation where it is determined that there is no vibration than in the situation where there is vibration. Can be switched to a larger value. Therefore, when there is almost no vibration in the optical system, the angular velocity signal S3 output from the synthesis circuit 36 is generated by the angular velocity signal S1 of the low-frequency stable gyro 30L up to a relatively high frequency component, and the gyro with good high-frequency characteristics. The phenomenon that the image fluctuates due to the drift caused by 30H is prevented.

  FIG. 6 is a flowchart showing the procedure for switching the switching frequency fC of the synthesis circuit 36 (synthesis gyro) in the CPU 16. First, the CPU 16 obtains a low-frequency stable gyro signal obtained from the angular velocity signal S1 of the low-frequency stable gyro 30L through the LPF 38 and the A / D converter 14 in FIG. 1 (step S10). Then, it is determined whether or not the value of the low-frequency stable gyro signal is smaller than a predetermined threshold A (step S12).

  If NO is determined, it is determined that there is vibration, and the switches SW1 and SW2 of the HPF 50 are turned off (see FIG. 5) by the switching signal output to the synthesis circuit 36, and the switching frequency fC is set to the predetermined value Fv (step). S14). On the other hand, if YES is determined in step S12, it is determined that there is no vibration, and the switches SW1 and SW2 of the HPF 50 are turned on by the switching signal output to the synthesis circuit 36, and the switching frequency fC is set to a predetermined value Fs greater than Fv. (Step S16).

  When the switching frequency fC of the synthesizing circuit 36 is set in this way, an integration process is performed on the angular velocity signal S3 output by the synthesizing circuit 36 (angular velocity signal output unit 10) of the switching frequency fC (step S18). The angular velocity signal S3 is converted into an angle signal. Then, the value of the angle signal is output to the D / A converter 18 (see FIG. 1) as a value indicating the movement target position of the image stabilizing lens 24 (step S20). When the above processing is completed, the processing from step S10 is repeatedly executed. As a result, the switching frequency fC of the synthesis circuit 36 is switched to a suitable value in accordance with the state of vibration of the optical system.

  Next, the processing of the CPU 16 when another method is used as a method for determining the presence or absence of vibration of the optical system will be described with reference to the flowchart of FIG. First, the CPU 16 acquires a low frequency stable gyro signal obtained from the angular velocity signal S1 of the low frequency stable gyro 30L through the LPF 38 and the A / D converter 14 of FIG. 1 for a certain time (step S30). Then, a difference D between the value of the low frequency stable gyro signal at each time point acquired during the predetermined time and the predetermined reference value B (the value of the low frequency stable gyro signal at the time of no vibration) is obtained (step S32). ) To obtain the sum ΣD (step S34).

  Subsequently, the CPU 16 determines whether or not the total value [Sigma] D is smaller than a predetermined threshold value C (step S36). If NO is determined, it is determined that there is vibration, the switches SW1 and SW2 of the HPF 50 are turned off by the switching signal output to the synthesis circuit 36, and the switching frequency fC is set to the predetermined value Fv as in the case of FIG. (Step S38). On the other hand, if YES is determined in step S36, it is determined that there is no vibration, and the switches SW1 and SW2 of the HPF 50 are turned on by the switching signal output to the synthesis circuit 36, and the switching frequency fC is set to Fs larger than Fv ( Step S40). The following step S42 and step S44 are the same processing as step S18 and step S20 of FIG. 6 (the description is omitted), and when the processing of step S44 ends, the process returns to step S30.

  As a method for determining the presence or absence of vibration of the optical system, a method for determining whether or not the low-frequency stable gyro signal is larger than a predetermined threshold as shown in FIG. 6, or a low-frequency stable as shown in FIG. In addition to the method of judging from the relationship between the magnitude of the gyro signal and time, the following modes can be considered. For example, a signal obtained from the low-frequency stable gyro 30L (low-frequency stable gyro signal) is compared with a signal obtained from the high-frequency characteristic gyro 30H in the same manner as the low-frequency stable gyro 30L. Although there is no change, it may be determined that there is no vibration when there is a change in the signal of the high frequency characteristic gyro 30H, and it may be determined that there is vibration in other cases.

  Next, the synthesis of the angular velocity signals S1 and S2 of the low-frequency stable gyro 30L and the high-frequency characteristic gyro 30H is not synthesized by the synthesis circuit 36 composed of analog circuits as in the above embodiment, but in a software manner. The case of combining will be described. Even in this case, the switching frequency fC of the composite gyro can be switched by software.

  FIG. 8 shows an image blur correction apparatus in which the angular velocity signals S1 and S2 of the low-frequency stable gyro 30L and the high-frequency characteristic gyro 30H are synthesized in software and the processing is performed by the CPU 16 that performs integration processing and the like. It is the block diagram which showed other embodiment. Note that the same reference numerals as those in FIG. 1 are assigned to the processing units that perform the same or similar processing as in FIG.

  An angular velocity signal S1 output from the angular velocity sensor (low frequency stable gyro) 30L and obtained through the DC cut unit 32L and the amplifier circuit 34L, and an angular velocity sensor (high frequency characteristic gyro) 30H output from the DC cut unit 32L and the DC cut unit 32H The angular velocity signal S1 obtained via the amplifier circuit 34H is taken into the CPU 16 via the LPFs 12 and 12 and the A / D converter 14 without being input to the synthesis circuit 36 as shown in FIG. As a result, the CPU 16 directly acquires the angular velocity signal from the low frequency stable gyro 30L and the angular velocity signal from the high frequency characteristic gyro 30H.

  The CPU 16 synthesizes the angular velocity signal from the low frequency stable gyro 30L and the angular velocity signal from the high frequency characteristic gyro 30H by arithmetic processing of a digital filter or the like, and generates an angular velocity signal similar to the output of the synthesis circuit 36, An integration process is performed on the angular velocity signal synthesized by the calculation to calculate the angle signal.

  Further, the CPU 16 determines the presence / absence of vibration of the optical system based on the angular velocity signal acquired from the low-frequency stable gyro 30L in the same manner as the processing described with reference to FIGS. Then, according to the determination, the multiplier in the arithmetic processing of the digital filter for synthesizing the angular velocity signal from the low frequency stable gyro 30L and the angular velocity signal from the high frequency characteristic gyro 30H is changed. As a result, the switching frequency fC is switched in the same manner as in the above embodiment according to the presence or absence of vibration.

  As described above, in the above embodiment, the switching frequency fC of the synthesis circuit 36 (synthesis gyro) is switched between the two values Fs and Fv. However, the present invention is not limited to this, and it depends on the state of vibration such as the magnitude of vibration. You may make it switch to more values than two. Further, when the switching frequency fC is switched from Fs to Fv or from Fv to Fs, the switching frequency fC may be gradually (stepwise or continuously) shifted from one value to the other value. Further, the values Fs and Fv at which the switching frequency fC is switched may be set to a desired value by the user.

  Moreover, in the said embodiment, although switching frequency fC was switched automatically, you may make it switch manually. Moreover, you may enable it to set not only a specific value but arbitrary values.

  In the above embodiment, the vibration applied to the optical system is detected by the angular velocity sensor, and the image blur correction is performed based on the angular velocity signal output from the angular velocity sensor. However, the vibration applied to the optical system is A vibration sensor other than the angular velocity sensor, such as an angular acceleration sensor, an acceleration sensor, a velocity sensor, an angular displacement sensor, or a displacement sensor, detects an image based on a vibration signal output from the vibration sensor corresponding to the vibration. The present invention can also be applied when shake correction is performed.

FIG. 1 is a block diagram showing the internal configuration of an image blur correction apparatus according to the present invention. FIG. 2 is a characteristic diagram comparing frequency characteristics of two angular velocity sensors used for vibration detection. FIG. 3 is a configuration diagram illustrating an example of a synthesis circuit in the angular velocity signal output unit. FIG. 4 is a diagram illustrating filter characteristics of the synthesis circuit. FIG. 5 is a configuration diagram showing an example of the HPF of the synthesis circuit. FIG. 6 is a flowchart illustrating a procedure of switching frequency switching processing in the CPU of the image blur correction apparatus. FIG. 7 is a flowchart showing the procedure of another embodiment of the switching frequency switching process in the CPU of the image blur correction apparatus. FIG. 8 is a configuration diagram showing another embodiment of the image blur correction apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Angular velocity signal output part, 12, 38 ... Low pass filter, 14 ... A / D converter, 16 ... CPU, 18 ... D / A converter, 20 ... Motor drive circuit, 22 ... Motor, 24 ... Anti-vibration lens, 30L: Angular velocity sensor (low frequency stable gyro), 30H: Angular velocity sensor (high frequency characteristic gyro), 32L, 32H: DC cut unit, 34L, 34H: Amplifier circuit, 36: Composite circuit

Claims (5)

An optical system for forming an image, a shake signal output means for outputting a shake signal corresponding to vibration applied to the optical system, an image displacement means for displacing the image, and a shake output by the shake signal output means In an image blur correction apparatus comprising: an image blur correction unit that displaces an image by the image displacement unit so as to cancel image blur due to vibration applied to the optical system based on a signal,
The shake signal output means includes
A first shake sensor that outputs a shake signal corresponding to vibration applied to the optical system, wherein the first shake sensor has low drift but poor frequency characteristics in a high-frequency region;
A second shake sensor for outputting a shake signal corresponding to vibration applied to the optical system, wherein the second shake sensor has more drift than the first shake sensor but has good frequency characteristics in a high frequency region. When,
The optical signal is obtained by acquiring from the first shake sensor a shake signal in a low frequency region lower than a predetermined switching frequency, and obtaining and synthesizing a shake signal in a higher frequency region than the switch frequency from the second shake sensor. A signal synthesizing means for generating a vibration signal for the entire frequency region of the vibration applied to the system;
Switching frequency changing means for changing the switching frequency in the signal synthesis means;
An image blur correction apparatus comprising:   2. The image blur correction apparatus according to claim 1, wherein the switching frequency changing unit changes the switching frequency based on a magnitude of vibration applied to the optical system.   3. The image blur correction apparatus according to claim 2, wherein the switching frequency changing unit detects the magnitude of vibration applied to the optical system based on a shake signal obtained from the first shake sensor.   The switching frequency changing means divides the magnitude of vibration applied to the optical system into a magnitude that is determined as no vibration and a magnitude that is determined as having vibration. 4. The image blur correction apparatus according to claim 2, wherein the switching frequency is increased as compared with a case where the magnitude is determined to be vibration.   5. The image blur correction apparatus according to claim 1, wherein the image displacement unit displaces the image by displacing a vibration-proof lens disposed in the optical system. 6.

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